That is a very hard question to answer, as it is all relative to the niche as well. There are some niches that are so dog eat dog, nobody really likes to one way link without something beneficial to them (MONEY). It just takes a lot of networking and trial & error. I go the slow and methodical way, I use MOZ and create a set of branded keywords and look for anybody using them. If I find a related site using the branded keywords I like. I simply send them a feeler email a few times. I'd say it works 20% of the time, but there is no real "do this and you get a backlink" strategy.